1. Field of the Invention
The present invention relates to a one-way rotational transfer mechanism having a rotary input shaft and a rotary output shaft which are coaxially arranged, wherein rotation of the rotary input shaft is transferred to the rotary output shaft when the rotary input shaft is rotated by, e.g., motor, but rotation of the rotary output shaft is not transferred to the rotary input shaft when rotary output shaft is rotated.
2. Description of the Related Art
Among conventional mechanisms having a rotary input shaft and a rotary output shaft, wherein rotation of the rotary input shaft is transferred to the rotary output shaft when the rotary input shaft is rotated by a motor, a mechanism which prevents the motor from being rotated by rotation of the rotary output shaft when the rotary output shaft is rotated is not known in the art. Note that the term xe2x80x9cone-way rotational transferxe2x80x9d used in the present specification and claims means to allow rotation of the rotary input shaft to be transferred to the rotary output shaft while preventing rotation of the rotary output shaft to be transferred to the rotary input shaft.
The present invention provides a simple one-way rotational transfer mechanism which allows rotation of the rotary input shaft to be transferred to the rotary output shaft while preventing rotation of the rotary output shaft from being transferred to the rotary input shaft.
According to an aspect of the present invention, a one-way rotational transfer mechanism is provided, including a rotary input shaft having an orthogonal surface lying in a plane orthogonal to an axis of the rotary input shaft, a hollow-cylindrical rotary output shaft positioned around the rotary input shaft to be freely rotatable relative to the rotary input shaft about the axis thereof, the hollow-cylindrical rotary output shaft having a cylindrical inner peripheral surface about the axis of the rotary input shaft, a circumferentially-uneven-width-space forming portion formed on the rotary input shaft to be adjacent to the orthogonal surface to form at least one accommodation space between the rotary input shaft and the cylindrical inner peripheral surface, at least one rotatable member installed in the accommodation space, and a biasing device for making the orthogonal surface and the rotatable member come into pressing contact with each other. The circumferentially-uneven-width-space forming portion is shaped so that a rotation of the rotary input shaft is transferred to the hollow-cylindrical rotary output shaft via the rotatable member to which the rotation is given from the orthogonal surface when the rotary input shaft is driven to rotate.
It is desirable for the rotatable member to be a ball.
The rotatable member can include a ball, and a ring in which the ball is loosely fitted. The ring is positioned in associated the accommodation space so that an axis of the ring extends substantially parallel to each of the axis of the rotary input shaft and an axis of the hollow-cylindrical rotary output shaft.
It is desirable for an axial length of the ring to be smaller than a diameter of the ball.
The rotatable member can include a cylindrical column roller which is positioned in associated the accommodation space so that an axis of the cylindrical column roller extends substantially in a radial direction of the rotary input shaft.
The rotary input shaft can include an outer flange on which the orthogonal surface is formed.
The circumferentially-uneven-width-space forming portion can be a portion having a non-circular cross section which includes at least one surface orthogonal to a radial direction of the rotary input shaft.
It is desirable for the circumferentially-uneven-width-space forming portion having the non-circular cross section to be in the shape of a polygon.
It is desirable for the circumferentially-uneven-width-space forming portion to include at least one pair of inclined surfaces which are symmetrical with respect to a line extending in a radial direction of the rotary input shaft.
The circumferentially-uneven-width-space forming portion can be an eccentric cylindrical surface which is eccentric from the axis of the rotary input shaft.
The one-way rotational transfer mechanism can include two parallel bearing plates, each having a boss, the rotary input shaft being fitted in respective central holes of the bosses so that the rotary input shaft is freely rotatable about an axis of the bosses.
The hollow-cylindrical rotary output shaft can be fitted on outer peripheral surfaces of the bosses to be freely rotatable about the axis of the rotary input shaft.
The circumferentially-uneven-width-space forming portion is positioned between the orthogonal surface and an end surface of one of the bosses, the end surface lying in a plane orthogonal to the axis of the rotary input shaft.
The biasing device can be a compression coil spring.
The one-way rotational transfer mechanism can include two parallel bearing plates, each having a boss, the rotary input shaft being fitted in respective central holes of the bosses so that the rotary input shaft is freely rotatable about an axis of the bosses. The biasing device can be a compression coil spring which is positioned between the outer flange and one of the bosses, and the circumferentially-uneven-width-space forming portion can be positioned between the orthogonal surface of the outer flange and an end surface of the other of the bosses, the end surface lying in a plane orthogonal to the axis of the rotary input shaft.
In another embodiment, a one-way rotational transfer mechanism is provided, including a rotary input shaft having a first orthogonal surface lying in a plane orthogonal to an axis of the rotary input shaft; a hollow-cylindrical rotary output shaft positioned around the rotary input shaft to be freely rotatable relative to the rotary input shaft about the axis thereof, the hollow-cylindrical rotary output shaft having a cylindrical inner peripheral surface about the axis of the rotary input shaft; a second orthogonal surface formed on a boss and lying in a plane orthogonal to the axis of the rotary input shaft to face the first orthogonal surface; a circumferentially-uneven-width-space forming portion formed on the rotary input shaft between the first orthogonal surface and the second orthogonal surface to form at least one accommodation space between the rotary input shaft and the cylindrical inner peripheral surface; at least one rotatable member installed in the accommodation space; and a biasing device which biases one of the rotary input shaft and the hollow-cylindrical rotary output shaft in a direction along the axis of the rotary input shaft to reduce a space between the first orthogonal surface and the second orthogonal surface so that the rotatable member is held tight between the first orthogonal surface and the second orthogonal surface. The circumferentially-uneven-width-space forming portion is shaped so that a rotation of the rotary input shaft is transferred to the hollow-cylindrical rotary output shaft via the rotatable member to which the rotation is given from the first orthogonal surface when the rotary input shaft is driven to rotate.
It is desirable for the rotatable member to be a ball.
The rotatable member can include a ball, and a ring in which the ball is loosely fitted. The ring is positioned in associated the accommodation space so that an axis of the ring extends substantially parallel to each of the axis of the rotary input shaft and an axis of the hollow-cylindrical rotary output shaft.
It is desirable for an axial length of the ring is smaller than a diameter of the ball.
The rotatable member can include a cylindrical column roller which is positioned in associated the accommodation space so that an axis of the cylindrical column roller extends substantially in a radial direction of the rotary input shaft.
The rotary input shaft can include an outer flange on which the orthogonal surface is formed.
The circumferentially-uneven-width-space forming portion can be a portion having a non-circular cross section which includes at least one surface orthogonal to a radial direction of the rotary input shaft.
It is desirable for the circumferentially-uneven-width-space forming portion having the non-circular cross section is in the shape of a polygon.
It is desirable for the circumferentially-uneven-width-space forming portion to include at least one pair of inclined surfaces which are symmetrical with respect to a line extending in a radial direction of the rotary input shaft.
The circumferentially-uneven-width-space forming portion can be an eccentric cylindrical surface which is eccentric from the axis of the rotary input shaft.
The one-way rotational transfer mechanism can include two parallel bearing plates, each having a boss, the rotary input shaft being fitted in respective central holes of the bosses so that the rotary input shaft is freely rotatable about an axis of the bosses.
The hollow-cylindrical rotary output shaft can be fitted on outer peripheral surfaces of the bosses to be freely rotatable about the axis of the rotary input shaft.
The circumferentially-uneven-width-space forming portion is positioned between the orthogonal surface and an end surface of one of the bosses, the end surface lying in a plane orthogonal to the axis of the rotary input shaft.
The biasing device can be a compression coil spring.
The one-way rotational transfer mechanism can include two parallel bearing plates, each having a boss, the rotary input shaft being fitted in respective central holes of the bosses so that the rotary input shaft is freely rotatable about an axis of the bosses. The biasing device includes a compression coil spring which is positioned between the outer flange and one of the bosses, and the circumferentially-uneven-width-space forming portion is positioned between the orthogonal surface of the outer flange and an end surface of the other of the bosses, the end surface lying in a plane orthogonal to the axis of the rotary input shaft.
In another embodiment, a one-way rotational transfer mechanism is provided, including a rotary output shaft, a hollow-cylindrical rotary input shaft positioned around the rotary output shaft to be freely rotatable relative to the rotary output shaft about an axis thereof, the hollow-cylindrical rotary input shaft having an orthogonal surface lying in a plane orthogonal to an axis of the hollow-cylindrical rotary input shaft, a circumferentially-uneven-width-space forming portion formed on the hollow-cylindrical rotary input shaft to be adjacent to the orthogonal surface to form at least one accommodation space between the rotary output shaft and an inner peripheral surface of the hollow-cylindrical rotary input shaft, at least one rotatable member installed in the accommodation space, and a biasing device for making the orthogonal surface and the rotatable member come into pressing contact with each other. The circumferentially-uneven-width-space forming portion is shaped so that a rotation of the hollow-cylindrical rotary input shaft is transferred to the rotary output shaft via the rotatable member to which the rotation is given from the orthogonal surface when the hollow-cylindrical rotary input shaft is driven to rotate.
It is desirable for the rotatable member to be a ball.
The rotatable member can include a ball, and a ring in which the ball is loosely fitted. The ring is positioned in associated the accommodation space so that an axis of the ring extends substantially parallel to each of the axis of the hollow-cylindrical rotary input shaft and an axis of the rotary output shaft.
It is desirable for an axial length of the ring to be smaller than a diameter of the ball.
The rotatable member can include a cylindrical column roller which is positioned in associated the accommodation space so that an axis of the cylindrical column roller extends substantially in a radial direction of the rotary output shaft.
The hollow-cylindrical rotary input shaft can include an inner flange on which the orthogonal surface is formed.
The circumferentially-uneven-width-space forming portion can include a portion having a non-circular cross section which includes at least one surface orthogonal to a radial direction of the rotary output shaft.
The portion having the non-circular cross section can be in the shape of a polygon.
It is desirable for the circumferentially-uneven-width-space forming portion to include at least one pair of inclined surfaces symmetrical with respect to a line extending in a radial direction of the rotary output shaft.
The circumferentially-uneven-width-space forming portion can be an eccentric cylindrical surface which is eccentric from the axis of the rotary output shaft.
The one-way rotational transfer mechanism can include two parallel bearing plates, each having a boss, the rotary output shaft being fitted in respective central holes of the bosses so that the rotary output shaft is freely rotatable about an axis of the two bosses.
The hollow-cylindrical rotary input shaft can be fitted on outer peripheral surfaces of the bosses to be freely rotatable about the axis of the rotary output shaft.
The circumferentially-uneven-width-space forming portion is positioned between the orthogonal surface and an end surface of one of the bosses, the end surface lying in a plane orthogonal to the axis of the rotary output shaft.
The biasing device can be a compression coil spring.
The one-way rotational transfer mechanism can include two parallel bearing plates, each having a boss, the rotary output shaft being fitted in respective central holes of the bosses so that the rotary output shaft is freely rotatable about an axis of the bosses. The biasing device includes a compression coil spring which is positioned between the inner flange and one of the bosses, and the circumferentially-uneven-width-space forming portion is positioned between the orthogonal surface of the inner flange and an end surface of the other of the bosses, the end surface lying in a plane orthogonal to the axis of the rotary output shaft.
In another embodiment, a one-way rotational transfer mechanism is provided, including a rotary output shaft; a hollow-cylindrical rotary input shaft positioned around the rotary output shaft to be freely rotatable relative to the rotary output shaft about an axis thereof, the hollow-cylindrical rotary input shaft having an orthogonal surface lying in a plane orthogonal to an axis of the hollow-cylindrical rotary input shaft; a second orthogonal surface formed on a boss to lie in a plane orthogonal to the axis of the rotary output shaft and to face the first orthogonal surface; a circumferentially-uneven-width-space forming portion formed on the hollow-cylindrical rotary input shaft between the first orthogonal surface and the second orthogonal surface to form at least one accommodation space between the rotary output shaft and an inner peripheral surface of the hollow-cylindrical rotary input shaft; at least one rotatable member installed in the at least one accommodation space; and a biasing device which biases one of the rotary output shaft and the hollow-cylindrical rotary input shaft in a direction along the axis of the rotary output shaft to reduce a space between the first orthogonal surface and the second orthogonal surface so that the rotatable member are held tight between the first orthogonal surface and the second orthogonal surface. The circumferentially-uneven-width-space forming portion is shaped so that a rotation of the hollow-cylindrical rotary input shaft is transferred to the rotary output shaft via the rotatable member to which the rotation is given from the first orthogonal surface when the hollow-cylindrical rotary input shaft is driven to rotate.
It is desirable for the rotatable member to include a ball.
The rotatable member can include a ball, and a ring in which the ball is loosely fitted. The ring is positioned in associated the accommodation space so that an axis of the ring extends substantially parallel to each of the axis of the hollow-cylindrical rotary input shaft and an axis of the rotary output shaft.
It is desirable for an axial length of the ring to be smaller than a diameter of the ball.
The rotatable member can include a cylindrical column roller which is positioned in associated the accommodation space so that an axis of the cylindrical column roller extends substantially in a radial direction of the rotary output shaft.
The hollow-cylindrical rotary input shaft can include an inner flange on which the orthogonal surface is formed.
The circumferentially-uneven-width-space forming portion can be a portion having a non-circular cross section which includes at least one surface orthogonal to a radial direction of the rotary output shaft.
It is desirable for the portion having the non-circular cross section to be in the shape of a polygon.
It is desirable for the circumferentially-uneven-width-space forming portion to include at least one pair of inclined surfaces symmetrical with respect to a line extending in a radial direction of the rotary output shaft.
The circumferentially-uneven-width-space forming portion can be an eccentric cylindrical surface which is eccentric from the axis of the rotary output shaft.
The one-way rotational transfer mechanism can include two parallel bearing plates, each having a boss, the rotary output shaft being fitted in respective central holes of the bosses so that the rotary output shaft is freely rotatable about an axis of the two bosses.
The hollow-cylindrical rotary input shaft is fitted on outer peripheral surfaces of the bosses to be freely rotatable about the axis of the rotary output shaft.
The circumferentially-uneven-width-space forming portion is positioned between the orthogonal surface and an end surface of one of the bosses, the end surface lying in a plane orthogonal to the axis of the rotary output shaft.
The biasing device can be a compression coil spring.
The one-way rotational transfer mechanism can include two parallel bearing plates, each having a boss, the rotary output shaft being fitted in respective central holes of the bosses so that the rotary output shaft is freely rotatable about an axis of the bosses. The biasing device includes a compression coil spring which is positioned between the inner flange and one of the bosses, and the circumferentially-uneven-width-space forming portion is positioned between the orthogonal surface of the inner flange and an end surface of the other of the bosses, the end surface lying in a plane orthogonal to the axis of the rotary output shaft.
The present disclosure relates to subject matter contained in Japanese Patent Application No.2002-171070 (filed on Jun. 12, 2002) which is expressly incorporated herein by reference in its entirety.